1. Field of the Invention
This invention relates to the field of connecting cylindrical metal pipe sections in endwise relationship to thus form a long string of sealed pipe.
2. Description of Prior Art
It is conventional practice to connect steel pipe sections used for water well casing, for gas pipe lines, etc., by means of welding. Each circumferential weld between the abutted ends of pipe sections takes a long time to make.
Various attempts have been made to connect pipe sections in the absence of welds or threads, but insofar as applicants are aware no prior-art solution has been sufficiently practical or successful to supplant to any substantial degree the conventional circumferential welding practice state above.
Among the inadequacies and deficiencies of the prior art known to applicants are the following: (a) The rings were insufficiently strong and elastic, and/or it was not realized that the rings should not be stretched beyond their elastic limit. (b) The relationships relative to size, amount of stretching, wall thickness, etc., were not such as to do a practical job of connecting the pipe sections. Furthermore, the materials employed were inadequate for the purpose. (c) Reliance was frequently placed on belling or outward bending of the pipe ends, instead of relying substantially entirely on extremely strong frictional gripping relationships resulting from enormous hoop stresses in strong elastic encircling alloy steel bands. (d) The sealing means were incorrect in material and/or location, or were impractical to employ. (e) No encircling clasp means was employed during the connection procedure to effect correct alignment and prevent improper connections and inadequate sealing. (f) There was frequently much structure inside the pipe, which interfered with flow of fluid therethrough and with movement of tools therethrough. (g) Gluing of the pipe sections in the rings was sometimes resorted to, and was inadequate for the purposes intended by the present applicants. In summary, the relative sizes, pressures, materials, shapes, etc., were not such as to permit achievement of the great, practical results which applicants have now achieved.